Pump system for a gas turbine engine

ABSTRACT

A pump system for a gas turbine engine including a first pump connected to a fluid flow demand line for delivering fluid to a fluid flow demand and a second pump connected, in parallel to the first pump, to the fluid flow demand line and supplementing fluid to the actuation or burner system based on the fluid flow demand. A pressure regulating valve (PRV) is fluidly connected to the flow demand line for bypassing flow to a pump inlet pressure of the first pump and second pump, and controlling a modulated pressure flow signal to a bypass valve, wherein the bypass valve is in fluid communication with the second pump and the PRV for receiving modulated pressure from the PRV and regulating delivery of fluid from the second pump to a bypass flow line.

BACKGROUND Technological Field

The present disclosure relates generally to an improved fuel pumpingsystem for a gas turbine engine, and more particularly to a pump systemhaving dual parallel pumps.

Description of Related Art

Gas turbine engines typically include a compressor compressing air anddelivering it to a combustion chamber. The compressed air is mixed withfuel in the combustion chamber, combusted, and the products ofcombustion pass downstream over turbine rotors, driving the rotors tocreate power.

There are many distinct features involved in a gas turbine engine. Asone example only, the compressor may be provided with variable vaneswhich are actuated to change an angle of incident dependent on systemconditions. Actuators for changing the angle of incident of the vanes,and any other actuator or flow demand needed for engine operation, areprovided with hydraulic fluid from a positive displacement pump. Whileconventional engines, components, and methods of designing aircraftengines have generally been considered satisfactory for their intendedpurpose there is still a need in the art for improved enginearchitecture that is more efficient and adaptable to extreme and typicalconditions. The present disclosure provides a solution for this need.

SUMMARY OF THE INVENTION

A pump supply system that can employ fuel for a gas turbine engine isdisclosed. The system includes a first positive displacement pumpconnected to a fuel flow demand line delivering fuel to an actuation orburner system based on a fuel flow demand, a second positivedisplacement pump connected to the fuel flow demand line in parallel tothe first pump supplementing fuel to the actuation or burner systembased on the fuel flow demand, a pressure regulating valve (PRV) fluidlyconnected with the first pump and the flow demand line for returningexcess flow to a bypass flow fuel line and controlling modulatedpressure to a bypass valve, which is in fluid communication with thesecond pump and the PRV for receiving modulated pressure from the PRVand regulating delivery of fuel from the second pump to a bypass flowfuel line. The system can include an aircraft burner or actuationsystem. The bypass valve can be hydraulically controlled. The first pumpand the second pump can be different sizes.

The PRV can be actuated by a first Electro-Mechanical Interface Device(EMID) which receives electronic signals from an Electronic EngineControl (EEC) which measures pressure at the fuel flow line fordelivering fuel to the actuation or burner system from the first pumpand from the second pump versus the required pressure for the actuationor burner system as determined by the EEC. A pressure sensor can beconnected to the fuel flow demand line, configured to measure demandflow pressure to the EEC. A second, independent EMID can be used forcontrolling the bypass valve. A second independent pressure sensor canbe connected to a fuel line connecting the bypass valve and the secondpump, configured to supply that pressure data to the EEC.

The system can include a first check valve and a second check valve forallowing flow from each of the pumps to the flow demand, wherein fuelflow from the first pump and the second pump to the actuation or burnersystem is controlled by a corresponding check valve. The PRV can receivebypass fuel flow from the first pump and provides bypass fuel flowdirected to the first pump and the second pump inlet. The PRV providesbypass fuel flow directed to the inlet of the first pump and the secondpump when the PRV is in at least a partially open position. The PRV isfluidically connected to pump inlet pressure and provides a pressuresignal to the bypass valve, with a high pressure signal being providedwhen the PRV is in a closed position and the signal pressure reducing topump inlet pressure as the PRV becomes more open.

The second check valve can be fully closed during a first mode. Thefirst check valve can be fully open during a first mode. The secondcheck valve can be fully open during a second mode.

The bypass valve can be closed during a second mode (to be described ashigh fuel demand conditions in the specification), allowing the secondpump to supplement fuel delivery to the actuation or burner system alongthe fuel flow demand line. The first check valve can be closed when thefirst pump is offline.

The PRV can be connected to the flow demand line by an orifice line. Theorifice line can include an orifice therein for supplying a highpressure flow from the flow demand to modulated pressure which isconnected to a signal window within the PRV, which provides flow to thepump inlet, thus reducing the modulated pressure the more open then PRVbecomes.

These and other features of the systems and methods of the subjectdisclosure will become more readily apparent to those skilled in the artfrom the following detailed description of the preferred embodimentstaken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

So that those skilled in the art to which the subject disclosureappertains will readily understand how to make and use the devices andmethods of the subject disclosure without undue experimentation,embodiments thereof will be described in detail herein below withreference to certain figures, wherein:

FIG. 1 is a schematic view of an embodiment of fuel supply systemaccording to the disclosure in a first condition;

FIG. 2 is a schematic view of the embodiment of fuel supply system ofFIG. 1 , showing two pumps providing fuel flow;

FIG. 3 is a schematic view of the embodiment of fuel supply system ofFIG. 1 , showing a situation when a first pump is not accessible; and

FIG. 4 is a schematic view of another embodiment of fuel supply systemaccording to the disclosure in a first condition.

DETAILED DESCRIPTION

Reference will now be made to the drawings wherein like referencenumerals identify similar structural features or aspects of the subjectdisclosure. For purposes of explanation and illustration, and notlimitation, a partial view of an exemplary embodiment of a fuel systemin accordance with the disclosure is shown in FIG. 1 and is designatedgenerally by reference character 100. Other embodiments of the system inaccordance with the disclosure, or aspects thereof, are provided inFIGS. 2-4 , as will be described. The system can be used with animproved engine architecture that is more efficient and adaptablebetween extreme and typical flight conditions and flow requirements.

Referring now to FIG. 1 , a fluid supply system 100 for a gas turbineengine is shown. The system 100 includes a first pump 102 connected to aflow demand line 122 delivering fuel to an actuation or burner system120 based on a fuel flow demand and a second pump 104 connected to thefuel flow demand line 122 in parallel to the first pump 102 forsupplementing the first pump 102. A pressure regulating valve 112 (PRV)is connected to the first pump 102. The PRV 112 is responsible forensuring that a proper amount of fuel is distributed from the first andsecond pump 102/104 to the actuation or burner system 120 and a bypassflow 131 that leads back to the inlet of the pumps 102/104. The PRV 112is also responsible for controlling modulated pressure 128 to the bypassvalve 118. The bypass valve 118 is responsible for modulating thepressure of the second pump 104. The system 100 can be used on anaircraft as part of a combustion or actuation system. The first pump 102and the second pump 104 can be different sizes i.e. having differentflow rate capabilities, different pressure capability, physical sizes,etc. allowing the system to be optimized for typical conditions and notbe sized for the extreme flow conditions.

Referring further to FIG. 1 , the PRV 112 is controlled by a first EMID110, from which it receives pressure command signals based on flowdemand 120. The EMID 110 receives signals from the Electronic EngineControl 108, which is responsible for controlling a plurality ofsystems. The EEC 108 receives pressure readings from the pressure sensor136 which measures pressure of the fuel flow demand line 122 andcompares it against required pressures. The PRV 112 bypasses flow inorder to regulate the pressure of the demand flow. The desired pressurecan be changed by adjusting the pressure in the spring cavity of thePRV. The pressure sensor provides pressure signal data to the EEC 108and depending on the pressure requested by the EEC 108, an electronicsignal is sent to the EMID 110 so that the EMID 110 will increase ordecrease the pressure signal to the spring cavity of the PRV 112, movingthe PRV 112 to a more closed or opened position, respectively, thusincreasing or decreasing the pressure of the demand flow as requested.It is also considered that a second, independent EMID 409 can be usedfor controlling the bypass valve 418 (as shown in FIG. 4 ). In thisconfiguration second independent pressure sensor 437 is also connectedto the fuel line connecting the bypass valve 418 and the second pump 404to supply pressure data to the EEC 408.

Referring again to FIGS. 1-3 , the system 100 includes a first checkvalve 114 and a second check valve 116, wherein fuel flow from the firstpump 102 and the second pump 104 to the actuation or burner system 120is controlled by a corresponding check valve 114/116. The PRV 112 canreceive fuel flow from the first pump 102 and provide bypass fuel flow131 directed to the inlet of the first and the second pump 102/104. Thefirst mode is where flow demand is low, for instance when actuators arenot moving so flow to the actuators is only enough to satisfy internalleakages in the actuation systems. In this mode, the first check valve114 is open and the second check valve 116 is closed sending flow fromthe second pump 104 to the bypass valve 118. Flow from the bypass valve118 is fed along line 134 to the bypass line 131 to be fed back to thefirst and second pump 102/104 inlet. The bypass valve 118 is also forcedopen by flow from the PRV 112 along line 128.

Referring now to FIG. 2 , a second mode of the system is shown. Thesecond mode includes high fuel demand when actuator(s) are commanded tomove, requiring flow from the pump to move them. During high flow demandthe second check valve 116 can be partially or fully open. Fuel from thesecond pump 104 supplements fuel flow from the first pump 102 along fueldemand line 122. As the fuel demand is high, the PRV 112 closes andlimits or stops flow from going to the pump inlet along line 131. ThePRV also closes a signal window 124 partially or completely, whichcauses the pressure signal to the bypass valve 118 to increase becauseof the high pressure fed to the modulated pressure line 128 by theorifice 132. Orifice 132 can be used for supplying a high pressure flowfrom the flow demand 120 to the modulated pressure line 128 which isconnected to signal window 124 in the PRV, which provides flow to thepump inlet, thus increasing the modulated pressure as the PRV closes.The increased signal pressure 128 forces the bypass valve 118 to closepartially or completely, which restricts or stops flow from the secondpump 104 to the bypass line 134. There is also an intermediate conditionwhere the second check valve 116 is at least partially open and bypassvalve 118 is partially open. As the signal pressure to the bypass valve118 increases, the bypass valve 118 will close more until it is fullyclosed.

Referring now to FIG. 3 , when the first pump 102 is offline, such asdue to a failure, the first check valve 114 closes. To maintain therequired fuel pressure, the PRV 112 closes and does not allow fuel flowto the pump inlet along line 131. The lack of flow through the signalwindow 124 in the PRV 112 increases the modulated pressure 128, whichforces the bypass valve 118 to close and not allow flow from the secondpump 104 to the bypass line 134 ensuring that flow is supported by thesecond pump 104.

Referring now to FIG. 4 , the PRV 412 is controlled by a first EMID 410,from which it receives pressure command signals based on flow demand420. A second, independent EMID 409 is be used for controlling thebypass valve 418. A second independent pressure sensor 437 is connectedto the fuel line connecting the bypass valve 418 and the second pump 404to supply pressure data to the EEC 408.

In FIG. 4 , the system is also shown in a first or low demand mode. Thefirst check valve 414 is open and the second check valve 416 is closedsending flow from the second pump 404 to the bypass valve 418. Flow fromthe bypass valve 418 is fed along line 434 to the bypass line 431 to befed back to the first and second pump 402/404 inlet.

In a traditional pumping system with one pump, the entire flow generatedby the pump is at the set pressure and becomes overdesigned forsituations where flow is low. In this instance, when the flow demand islow, one of the pumps is operating at a low pressure differential, thusreducing the power needed for pumping and reducing the amount of heatadded to the fuel. However, when flow demand increases, both pumps canprovide flow in parallel. Also, if one of the pumps fails, the otherpump can provide sufficient flow to safely land the aircraft. Thisfeature can, for example, improve safety and reliability.

The methods and systems of the present disclosure, as described aboveand shown in the drawings, are used with an improved engine architecturethat is more efficient and adaptable between extreme and typical flightconditions and flow requirements. While the systems and methods of thesubject disclosure have been shown and described with reference topreferred embodiments, those skilled in the art will readily appreciatethat changes and/or modifications may be made thereto without departingfrom the scope of the subject disclosure.

1. A pump system for a gas turbine engine comprising: a first pumpconnected to a fluid flow demand line delivering fluid to a fluid flowdemand; a second pump connected, in parallel to the first pump, to thefluid flow demand line and configured to supplement fluid to anactuation or burner system of the fluid flow demand based on a flowdemand; and a pressure regulating valve (PRV) fluidly connected to thefluid flow demand line for bypassing flow to a pump inlet of the firstpump and second pump, and controlling a modulated pressure flow signalto a bypass valve; an Electronic Engine Control (EEC) which measurespressure at the fluid flow demand line for delivering fluid to theactuation or burner system from the first pump and from the second pump;a first Electro-Mechanical Interface Device (EMID) which receiveselectronic signals from the EEC, wherein the EMID is configured toactuate the PRV; a pressure sensor connected to the fluid flow demandline configured to supply a demand flow pressure data signal to the EEC;and a second EMID for controlling the bypass valve, wherein the bypassvalve is in fluid communication with the second EMID via a pressurecommand line for receiving a pressure command from the EMID, and influid communication with the second pump for regulating delivery offluid from the second pump to a bypass flow line.
 2. The system of claim1, further comprising a first check valve and a second check valve,wherein fluid flow from the first pump and the second pump to the fluidflow demand is regulated by the first check valve and the second a checkvalve, respectively.
 3. The system of claim 2, wherein the PRV providesbypass flow directed to the inlet of the first pump and to inlet of thesecond pump when the PRV is in at least a partially open position. 4.The system of claim 2, wherein the bypass valve is in fluidcommunication with the PRV for receiving modulated pressure from thePRV, wherein the PRV regulates the pressure sent to the bypass valve byselectively opening or closing a portion of the PRV that sends flow tothe pump inlet.
 5. The system of claim 4, wherein the PRV provides flowfrom the inlet pressure to the bypass valve in at least a partially openposition.
 6. The system of claim 2, wherein the second check valve isfully closed during a first mode.
 7. The system of claim 2, wherein thefirst check valve is fully open during a first mode.
 8. The system ofclaim 2, wherein the second check valve is fully open during a secondmode.
 9. The system of claim 2, wherein the bypass valve is closedduring a second mode, allowing the second pump to supplement fluiddelivery to the actuation or burner system along the fluid flow demandline.
 10. The system of claim 2, wherein the first check valve is closedwhen the first pump is offline. 11-13. (canceled)
 14. The system ofclaim 1, further comprising a second independent pressure sensorconnected to a fluid line connecting the bypass valve and the secondpump configured to supply a pressure data signal to the EEC.
 15. Thesystem of claim 1, wherein the PRV is connected to the flow demand lineby an orifice line.
 16. The system of claim 15, wherein the orifice lineincludes an orifice therein for supplying a high pressure flow to amodulated pressure line.
 17. The system of claim 1, wherein the PRVcomprises a signal window for providing flow to the pump inlet.
 18. Thesystem of claim 1, wherein the fluid flow demand line delivers fluid toa burner or actuation system.
 19. The system of claim 1, wherein thefirst pump and the second pump are different sizes.
 20. The system ofclaim 1, wherein the system supplies fuel.